How do you get attribute values using XML::LibXML

[onegative]

I am trying to extract the attribute value of name but not sure what/how I am suppose to do so...can't find an actual real example.
Can someone help point me in the right direction?
Many Thanks..
file.xml

<HOSTNAME name='apple'>
<PATROL>
<ACL>
<USERNAME name='ml3007'>
<HOST>*</HOST>
<PERMISSION>COPS</PERMISSION>
</USERNAME>
</ACL>
</PATROL>
</HOSTNAME>

use strict;
use warnings;
use XML::LibXML;

  my $filename = $ARGV[0];

  my $parser = XML::LibXML->new();
  my $doc    = $parser->parse_file($filename);
  my $xc = XML::LibXML::XPathContext->new( $doc->documentElement()  );


  foreach my $sections ($xc->findnodes('/HOSTNAME/PATROL/ACL/USERNAME'
+)) {
    my($username) = $sections->getAttribute('name');
    my($permissions) = $sections->findnodes('./PERMISSION');
    my($host) = $sections->findnodes('./HOST');
    print $username->to_literal, "\n";
    print $permissions->to_literal, "\n";
    print $host->to_literal, "\n";
  }

[PeterPeiGuo]

Take away that "->to_literal()" method call after $username:

    print $username, "\n";
    print $permissions->to_literal, "\n";
    print $host->to_literal(), "\n";

[tofanikanudo]

Hi,
Method findnodes of XML::LibXML::XPathContext will return an array of elements or a XML::LibXML::NodeList object in case of scalar context.

So In above case, variable $section is a object of XML::LibXML::Element. Method getAttribute will return a scalar value if element has value of specified attribute.

So in above example $username has string value, not an element.

Thanks
Dhaval Patel

[grantm]

In the case where your XPath query will find only one node (e.g.: when referring to an attribute), instead of using findnodes, you could the findvalue method to get the text content of the matching node:

#!/usr/bin/perl

use strict;
use warnings;
use XML::LibXML;

my $filename = $ARGV[0];

my $parser = XML::LibXML->new();
my $doc    = $parser->parse_file($filename);
my $xc = XML::LibXML::XPathContext->new( $doc->documentElement()  );


foreach my $sections ($xc->findnodes('/HOSTNAME/PATROL/ACL/USERNAME'))
+ {
    my $username    = $sections->findvalue('./@name');
    my $permissions = $sections->findvalue('./PERMISSION');
    my $host        = $sections->findvalue('./HOST');
    print "$username\n";
    print "$permissions\n";
    print "$host\n";
}

Also, if your document doesn't actually use namespaces (which your example doesn't) then you might as well leave out XML::LibXML::XPathContext and call $doc->findnodes instead.

However if your document does use namespaces then instead of doing this:

$sections->findnodes('./PERMISSION');

You need to do this for the namespace prefixes to work:

$xc->findnodes('./PERMISSION', $sections);

[ikegami]

In addition to what's been said, it makes no sense to use an xpc in one place and not the other.

my $xc = XML::LibXML::XPathContext->new($root);
$xc->findnodes('/HOSTNAME/PATROL/ACL/USERNAME')
$sections->findnodes('./PERMISSION')

should be

$root->findnodes('/HOSTNAME/PATROL/ACL/USERNAME')
$sections->findnodes('./PERMISSION')

or

my $xc = XML::LibXML::XPathContext->new( $root );
$xc->findnodes('/HOSTNAME/PATROL/ACL/USERNAME')
$xc->findnodes('./PERMISSION', $sections)

An xpc isn't needed here since your XML doesn't use namespaces, but there's no harm in using one. Just be consistent about it.

Note that the leading to "./" is useless (whether an xpc is used or not). The following will do:

$xc->findnodes('PERMISSION', $section)